People have used groundwater for thousands of years, especially in arid regions such as the Middle East and North Africa, where hand-dug wells and subsurface tunnel systems collected and diverted it for early societies. These ancient methods amounted to skimming the shallow groundwater off the top of massive aquifer systems—the vast stores of invisible groundwater beneath the continents that account for more than 95 percent of all circulating fresh water on Earth.
That early skimming was limited by the primitive know-how of the time. But beginning in the 19th century, technological developments were opening our access to groundwater as advancements in drilling for extracting petroleum were spun off and developed for the water well industry.
Still, even into the 1940s, most pumping reached only shallow depths of less than 30 feet, removing water at modest rates. That changed radically after World War II, when more sophisticated pumping technology, as well as the cheap, petroleum-based energy to power it, came to the fore. Soon we were pumping so much water from aquifers that we were beginning to “overdraft” them—taking out more than could be replenished at sustainable rates.
Today, a little more than a half-century later, the world gets about 35 percent of its fresh water this way, making it a sizable—and quite new—development in world history.
This new availability of water, especially in arid regions, together with the advent of relatively cheap chemical fertilizers, has helped fuel the Green Revolution, increasing agricultural production around the globe, especially in the developing world. But it has come with a cost that cannot be sustained without new ways of managing our water resources.